The following abbreviations are herewith defined, at least some of which are referred to within the following description of the prior art and the present invention.
3GPP Third Generation Partnership Project
ACK Acknowledgement
BCS Block Check Sequence
BEP Bit Error Rate Probability
BLEP Block Error Rate Probability
BLER Block Error Rate
BSS Base Station System
BTS Base Transceiver Station
CPS Coding and Puncturing Scheme Indicator
CRC Cyclic Redundancy Check
CS Coding Scheme
DLMC Downlink Multi Carrier
EDGE Enhanced Data rates for GSM Evolution
EGPRS Enhanced GPRS
GERAN GSM EDGE Radio Access Network
GPRS General Packet Radio Service
GSM Global System for Mobile communications
LLC Logical Link Control
MAC Medium Access Control
MCS Modulation and Coding Scheme
MS Mobile Station
NACK Negative Acknowledgment
PACCH Packet Associated Control Channel
PAN Piggy Backed Ack/Nack
PDAN Packet Downlink Ack/Nack Message
RLC Radio Link Control
SF Stealing Flag
TBF Temporary Block Flow
TCP Transmission Control Protocol
TFI Transport Format Indicator
UAS EGPRS2 Uplink level A modulation and coding Scheme
UL Uplink
In wireless networks the radio interface uses protocols that operate in an acknowledged mode to ensure that packet data is transferred reliably from a radio access network node to a mobile station (MS). For instance, with the GPRS radio interface the MS sends Ack/Nack reports to a radio access network node (e.g., BSS) which indicate whether or not downlink data blocks sent by the BSS to the MS using the Radio Link Control (RLC) protocol were received correctly. The MS does this by including an Ack/Nack bitmap in the so called Packet Downlink Ack/Nack (PDAN) message. The BSS uses a polling mechanism to trigger the MS to send the Ack/Nack reports. In particular, the BSS sends a poll indication requesting the MS to send the PDAN message using a specific uplink radio block. In the RLC acknowledged mode, any damaged data block that was received by the MS will be resent by the BSS if the corresponding Ack/Nack bitmap element in the PDAN message indicates “Nack”. Similarly, when the BSS receives a PDAN message with an “Ack” indication for a given data block it indicates that the MS correctly received that data block and then the BSS can slide a RLC transmit window forward. In particular, when the BSS receives confirmation that the oldest outstanding transmitted data block has been correctly received by MS then the BSS will slide the lower edge of the RLC transmit window forward to reflect the next oldest transmitted data block for which an “Ack” is still pending. For more details about this RLC acknowledged mode of operation see 3GPP TS 44.060 V11.4.0 (2013-03) “3rd Generation Partnership Project; Technical Specification Group GSM/EDGE Radio Access Network; General Packet Radio Service (GPRS); Mobile Station (MS)—Base Station System (BSS) interface; Radio Link Control/Medium Access Control (RLC/MAC) protocol (Release 11). The contents of this document are hereby incorporated by reference herein.
Referring to FIG. 1 (PRIOR ART), there is a basic diagram of a radio access network node 100 (e.g., BSS 100) which is coupled to a radio access network 101 and multiple BTSs 102 (only two shown) where the BSS 100 is shown interacting via one of the BTSs 102 over the GPRS radio interface 104 with the MS 106 (only one shown) utilizing a relatively new mode of operation called Downlink Multi Carrier which is currently being standardized within GERAN. In this new mode of operation, the BSS 100 sends data blocks 1031, 1032 . . . 103n using multiple downlink carriers 1051, 1052 . . . 105x (each downlink carrier is used to transmit one or more data blocks) during each radio block period to the MS 106 which utilizes a wideband receiver to receive the data blocks 1031, 1032 . . . 103n on multiple downlink carriers 1051, 1052 . . . 105x thereby increasing the downlink bandwidth (throughput) (see FIG. 1's step 1). As in the past, the BSS 100 will send the MS 106 a poll indication 107 which triggers the MS 106 to send a PDAN message 109 (control message 109) (see FIG. 1's step 2—note the poll indication 107 could be sent using any one of the data blocks 1031, 1032 . . . 103n) and indicates a specific uplink radio block the MS is to use for sending the PDAN. However, the MS 106 will, for any given uplink radio block period, still only use a single uplink carrier 111 to send one PDAN message 109 (see FIG. 1's step 3) and will therefore have the challenge of keeping-up from an Ack/Nack perspective with the significantly increased rate at which it can receive the data blocks 1031, 1032 . . . 103n sent on the multiple downlink carriers (1051, 1052 . . . 105x) by the BSS 100.
The current solution where the MS 106 sends the PDAN message 109 with a coding scheme CS-1 is based on a scenario where the MS 106 is receiving, at most, two carriers 1051, 1052 per radio block period as in a Downlink Dual Carrier operation. However, when introducing the possibility for the MS 106 to receive more than two carriers 1051 and 1052 and up to sixteen carriers 1051, 1052 . . . 10516 which is possible in the Downlink Multi Carrier operation it is not sufficient for the MS 106 to respond with a single PDAN message 109 using coding scheme CS-1 as it may not allow the BSS 100 to advance the lower edge of the RLC transmit window forward at the same rate as it is sending the data blocks 1031, 1032 . . . 103n on the downlink carriers 1051, 1052 . . . 10516 to the MS 106. Even if the BSS 100 used an increased RLC transmit window size there would still be an imbalance in a rate at which the BSS 100 transmits downlink data blocks 1031, 1032 . . . 103n and a rate the MS 106 acknowledges these data blocks 1031, 1032 . . . 103n which results in the stalling of a downlink RLC engine at the BSS 100 and thereby result in a less than optimal downlink bandwidth (throughput).
Moreover, in order not to stall other layers which are located above the RLC protocol such as e.g., the Transmission Control Protocol (TCP) layer there must be sufficient uplink transmission bandwidth available to allow the MS 106 to send e.g., TCP Acks. The TCP Acks are carried as the payload within LLC packet data units which are in turn each sent using one or more uplink data blocks at the RLC layer, in addition to sending the PDAN messages 109 (i.e. control blocks) on the uplink. In other words, sending PDAN messages 109 at a rate that allows for maintaining a balance in the rate at which the BSS 100 transmits downlink data blocks 1031, 1032 . . . 103n and the rate the MS 106 acknowledges these data blocks 1031, 1032 . . . 103n must not be so uplink bandwidth intensive such that there is little room for the MS 106 to send uplink data blocks that provide “Acks” (i.e. uplink radio blocks that do not provide a PDAN) that may be required for successful operation of the higher layer protocols. In view of the foregoing, it can be appreciated that there is a need to address the aforementioned problems and other related problems so there is a balance between the rate at which data blocks 1031, 1032 . . . 103n are transmitted to the MS 106 utilizing the Downlink Multi Carrier operation and the rate at which the MS 106 acknowledges receipt of the data blocks 1031, 1032 . . . 103n.